[ 016/150] tty: set_termios/set_termiox should not return -EINTR

Greg Kroah-Hartman
2013-02-27T01:19:41Z

From: Oleg Nesterov <oleg@redhat.com>

commit 183d95cdd834381c594d3aa801c1f9f9c0c54fa9 upstream.

See https://bugzilla.redhat.com/show_bug.cgi?id=904907
read command causes bash to abort with double free or corruption (out).

A simple test-case from Roman:

// Compile the reproducer and send sigchld ti that process.
// EINTR occurs even if SA_RESTART flag is set.

void handler(int sig)
{
}

main()
{
struct sigaction act;
act.sa_handler = handler;
act.sa_flags = SA_RESTART;
sigaction (SIGCHLD, &act, 0);
struct termio ttp;
ioctl(0, TCGETA, &ttp);
while(1)
{
if (ioctl(0, TCSETAW, ttp) < 0)
{
if (errno == EINTR)
{
fprintf(stderr, "BUG!"); return(1);
}
}
}
}

Change set_termios/set_termiox to return -ERESTARTSYS to fix this
particular problem.

I didn't dare to change other EINTR's in drivers/tty/, but they look
equally wrong.

Reported-by: Roman Rakus <rrakus@redhat.com>
Reported-by: Lingzhu Xiang <lxiang@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/tty/tty_ioctl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -617,7 +617,7 @@ static int set_termios(struct tty_struct
if (opt & TERMIOS_WAIT) {
tty_wait_until_sent(tty, 0);
if (signal_pending(current))
- return -EINTR;
+ return -ERESTARTSYS;
}

tty_set_termios(tty, &tmp_termios);
@@ -684,7 +684,7 @@ static int set_termiox(struct tty_struct
if (opt & TERMIOS_WAIT) {
tty_wait_until_sent(tty, 0);
if (signal_pending(current))
- return -EINTR;
+ return -ERESTARTSYS;
}

mutex_lock(&tty->termios_mutex);